The need for Adjuvant Therapy in Colorectal Cancer patients following potentially curative surgery has prompted a program of immunotherapy and Chemoimmunotherapy in patients with Dukes' C lesions, which was initiated in April of 1973. A total of 112 patients have been entered on this study. Forty-eight patients received BCG alone and 64 patients received the combination of 5-Fluorouracil and BCG. The tumor-free interval and the overall survival were the clinical parameters chosen for evaluation of the therapeutic results. With the longest follow-up of 42 months, there is little difference between BCG alone and the combination of 5-FU plus BCG in terms of both the disease-free interval and the survival. Both treatment arms are significantly beneficial when comparison is made using the same clinical parameters in a group of historical controls who had surgery alone for Dukes' C lesions. When both treatment arms were combined to one group designated "Adjuvant Therapy", the striking observation is that the overall survival of this group is not only significantly better than that of the historical controls with Dukes' C who had surgery alone but approximates quite closely to the overall survival in a group of 143 patients who had Dukes' B lesions treated by surgery alone. This indicates that by the administration of Adjuvant Therapy (BCG or BCG plus 5-FU) we were able to shift the prognosis of patients with Dukes' C lesions towards that of patients with Dukes' B lesions. Recurrent tumor was detected in 48 patients and was closely correlated with progressive and persistent elevations in the carcinoembryonic antigen levels in the plasma of these patients. The pattern of relapse is of interest since local recurrence was most common among patients with primary lesions in the rectum and the rectosigmoid portions of the large bowel, whereas in patients with primary lesions proximal to the rectosigmoid the pattern of relapse was almost always in the form of distant metastasis. This updated analysis of the study indicates that the results reported in last year's report continues to hold up with even greater statistical significance when compared to controls.